BIRMINGHAM, Alabama - National Transportation Safety Board investigators have recovered the flight data recorders from the wreckage of the UPS cargo jet that crashed on Wednesday near Birmingham-Shuttlesworth International Airport.

Eric Weiss, a spokesman for the agency, confirmed that the devices, commonly called "black boxes," have been retrieved from the wreckage.

Robert Sunwalt, the NTSB board member who is in Birmingham with the team of investigators, said the fire that followed the crash had melted debris around the recorders, requiring the use of picks and shovels to retrieve them.

One of the recorders collects data and a second device records the flight crew's conversations.

In addition to the black boxes, investigators expected to retrieve other instrumentation that also recorded some flight data. The airplane's enhanced ground proximity warning system hardware was found in the 300-yard-long debris field and is among the instruments that record data and may hold answers, Sunwalt said.

The investigation at the site of the crash is expected to last five to seven days, and off-site interviews, data analysis and other work will continue for months.

NTSB and Federal Bureau of Investigation personnel could be seen this morning in the neighhorhoods nearest the crash site examining debris. The airplane struck power lines and trees before impact, leaving debris in the yards of some homes.

"We're off to a very good start," Sunwalt said. "The investigation is going just where it should and I'm confident we'll be able to figure out what happened."